Interpreting Dyno Results

[VaCat33]

Hi All

In pouring through all the documents that came along with my Tiger when I purchased it, I found this Dynometer Results Printout (See attached). The Dyno test was done in 2002 during the restoration...before the engine went into the car. As you can tell this was before all the hi-tech graphics common with modern software. Note the date...the computer did not know it was a new millenium. 9k on the engine since then.

So what does all this data mean? It was a freshly rebuilt engine so I doubt there is anything bad. How much HP/torque? I could not figure out which column. Anything else interesting?

Since readings were at the flywheel, I understand there is a loss of about 17-18% in the power at the rear wheels? Correct?

As background my Tiger's 260 has f4b intake, Holley 4v--465 cfm, and a Comp Cam.

Thanks, Jim

 

[michael-king]

The first sheet indicates you got 220.2hp @ 5051rpm and 245lbft at 4046 rpm

 

[0neoffive]

Old data

Results will be affected by both your current exhaust system and modern fuel mixes. The lean burn at normal cruise rpms was nice, but the torque is in the wrong place unless you always do 85mph or want to drop the rear gear ratio a tad. All in all, very acceptable results for a mild mannered 260 . . . . .

 

[michael-king]

Another thing to consider is that if the motor is on an engine stand it will pull higher power than in the engine bay as it does not have the cramped surrounds and heat associated issues, will not be held back by a full exhaust (may have had no headers even) may not have had an aircleaner on it.

Also when you go to a rolling road the results vary depending on what kind of setup they have, the single roller dynojet deliver about 15% higher results than the dual roller dyno-dynamics.

as for your figures.. motor looks healthyfor a 260... has good flat torque from 2200rpm to 4500rpm and power is about right for a lightly modded 260.

 

[TigerBlue]

Shift points

From 1 of 3 Charts:

Torque Peak at about 3,100 rpm. Interesting but not important. RPM is a multiplier of power. Actually pretty flat torque to 4,000 which is nice.

HP peak not clear but about 5,100 rpm. Max Acceleration in any gear.

At almost 6,000 rpm still making over 200 hp. Do not shift at 5,100 for best performance. Maybe 5,500 or a more.

Calibrate your tach before running 6,000!

Or if the lifters are hydraulic? They will act as a rev limiter.

Also the Dyno was an engine dyno not a chassis dyno. The corrected numbers relate to losses to accessories only something like 3% not the 15% drop at the wheels through the transmission and rear end.

Not on public roads

 

[VaCat33]

Thanks guys. Tell me if I have this right...The interpretations you provided seem to match my assessment by the on street performance.

My Tiger is okay off the line, but far from being really quick...but when cruising at 50, if I step on it, I am at 90 in no time.

Thanks again,

Jim

 

[cadreamn67]

I would say your experience pretty well matches what the numbers say you should expect.

Since torque (twisting force) gets to 240 or so at 3000 rpm, that to me is a very important rpm number. I would plan my up-shift points so that the rpms drop to around 3000 when I am in the next higher gear. That will put you up on the cam at the beginning of that strong part of the curve as they say and give you the maximum acceleration in that gear. Thus you probably will not be winding out to red-line in the intermediate gears to get maximum acceleration, if that is what you are looking for at the time.

I would expect you are turning around 2200 or so in 4th at 50 mph. I bet if you downshifted to 3rd and punched it you might find a very strong jump in acceleration. Even more than the strong pull you already are getting in 4th. Be ready and in safe conditions if you do!

Cheers, Gene